Events

The Department of Civil and Environmental Engineering is pleased to announce Michael Noddings's MS Project Presentation: "Investigation Into Capacity Design Requirements for the Design of Columns in Eccentrically Braced Frames."

Eccentrically braced frames utilize inelastic links as a means of energy dissipation for the lateral loads resulting from an earthquake. The AISC design requirements for eccentrically braced frames necessitate that capacity design principals be used for the design of all sec¬tions that are located outside of the inelastic link region of the frame. Due to the capacity design requirements, the columns of eccentrically braced frames can become excessively large when repeating members are used which may lead to higher overall project costs. The intent of this research was to show through nonlinear time his¬tory analysis of eccentrically braced frames that the requirements for the strength of col¬umns was excessively large for eccentrically braced frames that utilized repeating links for design. To investigate the overstrength requirements for columns an analytical approach was used with the nonlinear structural analysis program SAP 2000. For nonlinear static analysis, pushover simulations were performed that used the static loading determined per ASCE. For the nonlinear time history analysis, the FEMA far field earthquake set was used which consisted of 22 earth¬quakes that each had 2 components for a total of 44 unique time histories. Three buildings that utilized eccentrically braced frames as the lateral force resisting system were investi¬gated. To test the column strength requirements set forth by AISC, the frames that made up the buildings were tested individually by applying mass to the frames and using the earthquakes from the FEMA far field set. Of the frames that were tested, results showed that the column overstrength that was required by AISC was a conservative approach when eccentrically braced frames were designed using repeating links.